The high-speed digital-to-analog (D/A) converter has been extensively applied to consumer electronics and communication technology. Refer to FIG. 1. In the conventional test method for the D/A converter (DAC) 1, a precision analog signal measurement circuit 3 containing a sample-hold circuit 4 is arranged in the output 2 of the D/A converter 1. The performance, especially the accuracy and stability, of the sample-hold circuit 4 directly influences the correctness of the measurement results. However, the design for a high-speed or high-resolution hold-sample circuit is hard to realize.
The tested signals are usually converted into special test eigenvalues to facilitate analysis. The test eigenvalues are converted into the frequency or the duty ratio of pulse signals, whereby the digital counting signals can be used to measure analog signals. However, the abovementioned technology needs a high-speed circuit to match the high-speed DAC, which greatly increases the difficulty of design.